Energy efficiency is an important aspect of wireless telecommunication systems. There are many solutions, and they are found in protocols, algorithms and hardware etc. Normally traffic load in the radio network varies; resource utilization is fluctuating between night (normally low) and day (normally high); in night time the spare capacity is running unutilized in the radio network. One approach is to halt partial radio resources during low traffic hours such as between 22.00 and 04.00.
However, legacy wireless telecommunication systems are not built specifically with energy efficiency in mind so solutions are often gross grained. For example it may only be possible to stop a complete cell from transmitting and receiving (discontinuous transmission). Using this approach may result in loss of coverage because capacity is lost since the cell is taken down. As a result it must first be verified that there is radio coverage in the area served also after stopping cell transmission.
Hence, there exists a need for a method and a system for taking a cell or a site into discontinuous transmission (sleep mode) without risking the coverage of its users, i.e. active or idling User Equipments (UEs).